US3794916A
Expired / Lapsed
US
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Digital voltmeter
Assignee: HP Inc
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Filing: 1972-03-09
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Granted: 1974-02-26
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Expires: 1992-03-09
Abstract
Abstract A digital voltmeter wherein the DC voltage to be measured is converted into a linear current which in turn is converted into a proportional voltage used to drive a voltage tunable oscillator producing an output pulse train with a repetition rate proportional to the input voltage, a digital counter system being utilized to count the pulses and record the count on a digital display. In one embodiment, the voltmeter measures positive input voltages in voltage increments producing 1 Hz pulse rate changes over a range of 1,000 Hz. In a second embodiment the voltmeter measures both positive and negative incoming voltages, with means for indicating to the operator the sign of the measured voltage.
Inventors
- 👤 J Ritzenthaler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:05
CPC Classifications
H; H03; H03K; H03K21/00; H03K21/08; G; G01; G01R; G01R19/00; G01R19/25; G01R19/252; H03M; H03M1/00; H03M1/12; H03M1/50
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
195 words
A signal measuring apparatus comprising: pair of input terminals; first means for converting a unidirectional input signal to a current value which varies above a non-zero idling current value in proportion to the magnitude of the unidirectional input signal, said non-zero idling current value corresponding to a zero value unidirectional input signal; second means coupled to the first means and responsive to said current value for producing a series of pulses having a pulse rate which is proportional to said current value, said second means also having a reference pulse rate in response to the non-zero idling current value; counter means coupled to the second means for counting the series of pulses in accordance with a selected radix to provide a counter output having a non-zero most significant digit manifestation and zeroes for lesser significant digit manifestations in response to the non-zero idling current value; display means coupled to the counter means and being responsive to said counter output for displaying only said lesser significant digit manifestations thereof representing the unidirectional input signal, said display means displaying the zero digits of the reference pulse rate count in response to a zero value unidirectional input signal.
Claim 2
Dependent Claim
195 words
A signal measuring apparatus comprising: pair of input terminals; first means for converting a unidirectional input signal to a current value which varies above a non-zero idling current value in proportion to the magnitude of the unidirectional input signal, said non-zero idling current value corresponding to a zero value unidirectional input signal; second means coupled to the first means and responsive to said current value for producing a series of pulses having a pulse rate which is proportional to said current value, said second means also having a reference pulse rate in response to the non-zero idling current value; counter means coupled to the second means for counting the series of pulses in accordance with a selected radix to provide a counter output having a non-zero most significant digit manifestation and zeroes for lesser significant digit manifestations in response to the non-zero idling current value; display means coupled to the counter means and being responsive to said counter output for displaying only said lesser significant digit manifestations thereof representing the unidirectional input signal, said display means displaying the zero digits of the reference pulse rate count in response to a zero value unidirectional input signal.
Claim 3
Dependent Claim
51 words
Signal measuring apparatus as in claim 1 wherein the first means includes a current source responsive to the unidirectional input signal, said current source varies the current output in proportion to the magnitude of the unidirectional input signal for increasing or decreasing the pulse rate linearly from the reference pulse rate.
Claim 4
Dependent Claim
127 words
A signal measuring apparatus as in claim 2 wherein the counte means includes: counters coupled to the display means; first logic means coupled between the display means and the counterS for registering a digital count on the display means for either an increasing or a decreasing pulse rate from the reference pulse rate, said first logic means includes a 9''s complement circuit coupled between the counters and the display means for registering an increasing count from the decreasing pulse rate of a negative unidirectional input signal; and second logic means coupled to the display means for indicating the polarity of the unidirectional input signal and a condition of overloading where the magnitude of the unidirectional input signal exceeds the measurable signal range of said signal measuring apparatus.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |